Closing Part a Two Threads Mos Density Opened and the Turn Toward Linear Ics

# Closing Part A: Two Threads MOS Density Opened, and the Turn Toward Linear ICs

## 1. Two Named Threads Forward

Part A closes here having covered the first commercial MOS integrated circuits, from General Microelectronics' and Electronic Arrays' earliest shift-register and calculator chips through the yield problems, the crowded competitive field, and the turn toward memory that Intel's founding represented. Two forward threads are named, not retold: `microprocessor_1971`, the series covering how a calculator chip's general-purpose logic eventually became a general-purpose processor, and `dram_1968`, the series covering memory's own structural engineering story starting from the recognition that memory needed a fundamentally different cell structure than logic.

Both of those series are already drafted in this directory as informal, not-yet-deployed ten-step series, and neither is this series' job to summarize; this step's job is only to mark that both threads trace back to the same commercial proof this series just walked through — that MOS density, once manufacturable at volume, was worth paying for.

## 2. The Turn Toward a Genuinely Different Product Category

Part B, starting at step 11, turns to a different and genuinely separate commercial story: linear integrated circuits, built mostly in bipolar process technology rather than MOS, solving a different kind of engineering problem — continuous analog signal fidelity rather than binary switching — but built in the same era, often inside the very same companies, including Fairchild, whose analog group was doing its own landmark commercial work while the company's MOS alumni were founding General Microelectronics and Intel. Same era, same fabs, often the same companies, genuinely different product categories — the relationship the next ten steps make explicit rather than assumed.